A three-dimensional memory has been known as an example of a semiconductor device. The three-dimensional memory includes a stacked body having a plurality of conductive layers alternating with a plurality of insulating layers. An end of the stacked body is formed in a step-shaped, and a contact hole is formed in each of the steps. A contact is in the contact hole, and the contact contacts each of the conductive layers.
Conventionally, one contact hole has been formed for one conductive layer. Thus, if the number of conductive layers increases, the depth of a contact hole corresponding to the conductive layer on the lower layer side increases. As a result, an aspect ratio (depth/hole diameter) increases so that a manufacturing failure of the contact easily occurs.